The first televised presidential debate took place on May 21, 1956, when an ABC affiliate in Miami broadcast a Democratic primary debate between Adlai Stevenson and Estes Kefauver. In the general election that year, Stevenson and incumbent President Dwight Eisenhower (R) used surrogates in a televised debate on November 4, 1956. They were represented by former First Lady Eleanor Roosevelt (D) and Sen. Margaret Chase Smith (R), respectively.

https://ballotpedia.org/Democratic_presidential_primary_debate_(February_7,_2020)